A Resonant Pressure Microsensor Based on Double-Ended Tuning Fork and Electrostatic Excitation/Piezoresistive Detection.

Xiaoqing Shi,Bo Xie,Yulan Lu,Deyong Chen,Jian Chen,Yadong Li,Junbo Wang

doi:10.3390/s18082494

Abstract

This paper presents a resonant pressure microsensor relying on electrostatic excitation and piezoresistive detection where two double-ended tuning forks were used as resonators, enabling differential outputs. Pressure under measurement caused the deformation of the pressure sensitive membrane, leading to stress buildup of the resonator under electrostatic excitation with a corresponding shift of the resonant frequency detected piezoresistively. The proposed microsensor was fabricated by simplified SOI-MEMS technologies and characterized by both open-loop and closed-loop circuits, producing a quality factor higher than 10,000, a sensitivity of 79.44 Hz/kPa and an accuracy rate of over 0.01% F.S. In comparison to the previously reported resonant piezoresistive sensors, the proposed device used single-crystal silicon as piezoresistors, which was featured with low DC biased voltages, simple sensing structures and fabrication steps. In addition, the two double-ended tuning forks were used as resonators, producing high quality factors and differential outputs, which further improved the sensor performances.

Highlights

Nowadays, micro pressure sensors are widely used in the fields of aerospace and meteorology [1].There are several common types of pressure sensors, such as capacitive pressure sensors [2,3], piezoresistive pressure sensors [4,5], piezoelectric pressure sensors [6,7] and resonant pressure sensors [8,9]
Depending on different excitation and detection mechanisms, resonant pressure sensors can be classified into electrothermal excitation and piezoresistive detection [11,12], electromagnetic excitation and electromagnetic induction detection [13,14,15], electrostatic excitation and piezoresistive detection [16,17] electrostatic excitation and capacitive detection [18,19,20]
This study presents a resonant pressure sensor relying on electrostatic excitation and piezoresistive detection where differential resonators based on double-ended tuning forks are used

Summary

Introduction

Micro pressure sensors are widely used in the fields of aerospace and meteorology [1].There are several common types of pressure sensors, such as capacitive pressure sensors [2,3], piezoresistive pressure sensors [4,5], piezoelectric pressure sensors [6,7] and resonant pressure sensors [8,9]. Depending on different excitation and detection mechanisms, resonant pressure sensors can be classified into electrothermal excitation and piezoresistive detection [11,12], electromagnetic excitation and electromagnetic induction detection [13,14,15], electrostatic excitation and piezoresistive detection [16,17] electrostatic excitation and capacitive detection [18,19,20]. Among the different excitation mechanisms, in electrothermal excitations, alternative currents are applied on resistors to produce cyclic thermal stresses to vibrate the resonant beams. This excitation mechanism is not favorable due to its high energy consumption. Alternative currents are applied on the resonant beams, which vibrate due to the induced ampere

Methods

Results

Conclusion